1. Field of the Invention
The present invention relates to an address assignment method, for use in a communication system composed of a plurality of communication stations communicating with each other via a data transmission line, which is used to assign a unique address to each communication station to identify itself. In particular, the present invention relates to an address assignment method which allows each of a plurality of communication stations to assign a unique address to itself through an easy processing procedure and, at the same time, increases the throughput of the whole system at address assignment time. The present invention also relates to a communication system to which this address assignment method is applied.
In addition, the present invention relates to an address assignment method, for use in a communication system composed of a plurality of communication stations each with one or more child nodes and communicating with each other via a data transmission line, which is used to assign a unique address to each communication station and to each child node to identify themselves. In particular, the present invention relates to an address assignment method which allows each of a plurality of communication stations to assign a unique address to itself and to each of its child nodes through an easy processing procedure and, at the same time, increases the throughput of the whole system at address assignment time; the present invention also relates to a communication system to which this address assignment system is applied.
2. Description of the Related Art
Conventionally, a communication system composed of a plurality of communication stations connected with each other for communication via a data transmission line has been known.
To exchange data among communication stations in the conventional communication station described above, it is necessary to assign, in advance, an address to each communication station to identify itself.
Conventionally, an address assignment method, such as the one disclosed in Japanese Patent Laid-Open Publication No. Hei 4-326896, is known where at least one master station and a plurality of slave stations are connected to the same communication bus.
The communication system disclosed in the above publication has the following configuration. Each slave station comprises storage means for updating its own communication address and connection requesting means for sending its own connection request information to the master station at communication system startup. The master station comprises communication address assignment means for assigning a unique communication address, different from that of any other slave station, to a requesting slave station when it receives the above-mentioned connection request information and for informing the slave station of the assigned communication address.
In this communication system, the connection requesting means of each slave station sends its own connection request information to the master station during communication system startup. Upon receiving connection request information from a slave station, the address assignment means of the master station assigns a communication address, different from that of any other stave station, to the slave station and informs the slave station of the assigned communication address. Therefore, even if a plurality of slave stations are connected to the same communication bus, each slave station is assigned an address which uniquely identifies itself.
However, the address assignment method of the conventional communication system has the following problem. That is, upon receiving connection request information from each slave station, the master station assigns a communication address different from that of any other slave station and returns the assigned communication address to the slave station individually. This configuration makes the processing procedure complicated when data (such as connection request information, communication address, and so on) is exchanged between the master station and each of a plurality of slave stations.
Another problem is that the total period of time required for data to be exchanged, or the time required for address assignment, tends to become long. As a result, it is difficult to increase the throughput of the whole communication system at address assignment time.